The present invention relates generally to structures that are deployable in space, and specifically to structures and methods that are used to deploy areas of flat films, membranes, or blankets.
Deployable array structures for use on spacecraft, satellites, and the like, have been developed in many forms. Generally, solar array structures consist of a plurality of rigid honeycomb panels, which are flat-folded for storage along one dimension, like an accordion pleat, and are extendable outwardly from a spacecraft in a simultaneous or sequential manner. One example of such a configuration of panels is described in U.S. Pat. No. 5,487,791.
A number of existing technologies used in space require deployment of large flat areas or “blankets,” such as photovoltaic (PV) blankets, membrane synthetic aperture radar (SAR) blankets, and electromagnetic (e.g., sunlight) shield blankets. The art of deployable space structures is most highly developed for solar arrays utilizing photovoltaic elements, which are the most common applications for deployable space structures.
Existing approaches to deploying a photovoltaic blanket are described in U.S. Pat. No. 5,961,738. These existing systems typically deploy blankets in one direction using one or more linear deploying booms, which spread out parallel structure beams or plates between which the blankets may be tensioned. These systems generally stow into a volume characterized in one dimension as approximately the width of the deployed array.
Power requirements for modern spacecraft have been rapidly increasing in recent years. As a result, increasingly larger-area solar arrays have been developed to meet these power needs. As the number and size of solar array panels is increased, the mass moment of inertia of the corresponding systems is also increased. This increase in mass moment of inertia is detrimental to array design and to spacecraft performance.
In response to these problems, systems that fold in two directions have been developed to counteract the detrimental growth in inertia brought about by larger-area arrays. An example of such a deployment using rigid panels is described in U.S. Pat. No. 6,010,096. These types of systems generally include panels that fold out linearly from the spacecraft, in an accordion fashion, and also laterally to obtain a lower aspect ratio and thus produce a lower mass moment of inertia.
The mass moment of inertia of the system may also be reduced by minimizing the overall mass of the deployable array structure, which in turn reduces the cost for launch. One problem resulting from existing blanket array structures is that they do not permit efficient tiling of individual blankets to produce a large array that satisfies modern power requirements. Further, existing array structures are designed specifically for deploying solar blankets, and thus are not suitable for use in deploying other types of flexible blanket members, such as synthetic aperture radar blankets, and electromagnetic shielding blankets (e.g., sun shield blankets).
Thus, there is a need for a readily deployable, lightweight, modular frame structure that allows for practical incorporation of flexible blanket assemblies, particularly solar blankets. Additionally, there is a need for an array structure that is compactly stowable, and that provides an optimal deployed aspect ratio for the system.